# this opens the answers file for append
open(ANSFILE,">>answers.txt") or die "Couldn't open answers for appending: $!\n";

# rather than a while loop and a variable just use a foreach # loop with a range ... $_ will contain the number

foreach(1 .. 10) {
     print $questions[ int( rand( scalar(@questions) ) )];
     my $ans = uc(<STDIN>);
     print ANSFILE $ans;
}
close(ANSFILE);
exit;